Premagnetized inductive device



1958 P. J H. JANSSEN ET AL 2,822,528

PREMAGNETIZED INDUCTIVE DEVICE Filed Sept. 28, 1955 INVENTORS PETER JOHANNES HUBERTUS JAN SSEN and JELLE DE VRIES BY 222W AGENT United States Patent PREMAGNETIZED INDUCTIVE DEVICE Peter Johannes Hubertus Janssen and Jelle de Vries, Eindhoven, Netherlands, assignors, by mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application September 28, 1955, Serial No. 537,177

Claims priority, application Netherlands October 15, 1954 2 Claims. (Cl. 336110) The invention relates to a device comprising a coil having a rod-shaped open core that is premagnetized by the use of permanent magnetism, particularly for correcting the linearity of the deflection current in a television receiver.

It is an object of the invention to provide a device of the above-described kind which can readily be massproduced and by means of which the value of the bias or premagnetization of the core can be adjusted in a simple manner.

According to the invention the coil is secured in a central bore of a block-shaped insulating support in which further bores are provided so as to surround the coil and to extend parallel thereto, and rod-shaped permanent magnets are arranged in at least a number of said bores.

Figures 1 and 2 of the drawing are an axial cross-sectional view and a plan view respectively of an embodiment.

The device shown in Figures 1 and 2 comprises a coil having a rod-shaped open ferromagnetic core 1 which is made, for example, of cubic ferrite material and a winding 3 provided on said core. The coil 1, 3 is arranged in a cylindrical bore or duct 5 of a likewise cylindrical support 7 made of non-magnetic insulating material, for example synthetic resin. The duct 5 is arranged coaxial ly with the support 7 and is surrounded by a number of, in the case shown six, further bores or ducts 9, 11, 13, 15, 17 and 19 which extend so as to be parallel to the duct 5.

In each of the said duets, with the exception of the duct 19, is arranged a rod-shaped permanent magnet 21, 23, 25, 27 and 29 respectively made of magnet steel or of a ceramic permanent magnetic material, poles of like nature being arranged in the same direction in each rod, so that the rods act in support of each others magnetizing effect upon the core rod 1. The value of the resulting bias magnetisation of the core 1 depends upon the number of magnet rods which surround the core and consequently is adjustable in a simple manner, by the choice of the number of rods, in a number of steps, in the present case in six steps. After the coil and the magnets have been arranged in the respective ducts they may be fixed therein by means of wax or lacquer or a suitable embedding mass.

When the support 7 is made of thermoplastic material it may be secured to a supporting plate or base 33 by means of a projection 31 which is provided at its bottom and comprises a head after the manner of a rivet.

As the above will show, adjustment is obtained exclusively by the use of stationary parts which may be very simple and cheap. The adjustment is not continuous; however, this is not inconvenient in a variety of uses. The device described has proved to be particularly suited for use in the device which is known per se for linearising the sawtooth current in a television apparatus with the use of a coil comprising a core provided with bias magnetisation.

What is claimed is:

1. An inductive device comprising a supporting member of non-magnetic, insulating material and having a central receiving aperture and a plurality of further receiving apertures substantially surrounding said central aperture, an end of each of the apertures being exposed to the outside, a rod-like core and coil mounted on said core, said core and coil being mounted in said central aperture, a plurality of rod-like permanent magnets each detachably secured in one 'of said further apertures, said rod-like magnets being magnetized all in the same direction and extending substantially parallel to said rod-like core, said permanent magnets being provided in quantities and in a distribution relative to the core at which the latter attains a predetermined degree of premagnetization, and means for mounting said supporting member onto a base.

2. An inductive device comprising a non-magnetic, block-like, insulating, supporting member having a plurality of substantially parallel bores including one within and surrounded by the others and accessible from a surface of said supporting member, a winding surrounding a substantially rod-like, magnetic, core member mounted within said one bore, and a plurality of rod-like, fixed, permanent magnets, all magnetized in the same direction and capable of premagnetizing the said core member, each detachably secured completely in one of said other bores, said magnets being provided in quantities and in a distribution relative to the said core member at which the latter attains a predetermined degree of premagnetization, said magnets all occupying a single position completely within their respective bore.

References Cited in the file of this patent UNITED STATES PATENTS 2,503,155 Harvey et al. Apr. 4, 1950 2,581,202 Post Jan. 1, 1952 2,691,768 Janssen Oct. 12, 1954 FOREIGN PATENTS 691,841 Great Britain May 20, 1953 516,578 Belgium June 27, 1953 

